Answer:
C. The number of positive and negative charges can be the same.
Explanation:
Choice-B is the true one.
Answer: 
Explanation:
Centripetal acceleration 
is calculated by the following equation:
Where:
is the Earth's orbital speed
is the orbital radius
Answer:
Wolves are a keystone species because they are so important to the ecosystem that their removal causes a catastrophic disequilibrium.
Explanation:
Wolves are the predators available in the environment but they exist in relatively less number while comparing it with another species of animals. Wolves influence their pray which are influenced by plants. Thus, They are so important to the ecosystem that their removal causes a catastrophic disequilibrium.
